The isoindolone fragment of cytochalasin D has been assembled by Diels-Alder reaction of an optically active N-benzoyl pyrrolinone intermediate with a substituted diene. This intermediate will be taken on to analogs of cytochalasin D by a ring expansion sequence where a 6-membered sulfide ring is bridged across the alpha, alpha' positions by a 6-carbon chain. The result of this reaction would be to complete the 11-membered carbocyclic periphery of cytochalasin D.